The purpose of this project is to exploit unique reproductive characteristics of the domestic cat and its wild relatives to improve our fundamental understanding of fertilization and embryogenesis. Findings are relevant to: (1) basic studies of fertilization mechanisms, gametogenesis, and early embryogenesis; (2) the significance of sperm pleiomorphisms; (3) propagation of genetically valuable laboratory animals and endangered species; and (4) genetic mapping studies and plans to deliver molecularly cloned genes into early-staged pre-implantation embryos. Understanding the events spanning sperm capacitation to implantation ensures the propagation of feline models useful for studying human diseases. The cat is a model for at least 36 human physiological abnormalities ranging from oncologic dysfunctions to leukemia transmission, a condition caused by an immune suppressing retrovirus similar to the retrovirus, HTLV-III, causing AIDS. Whereas feral cats reproduce well, the propagation of laboratory cats is difficult. Artificial breeding (e.g., artificial insemination [AI] and in vitro fertilization [IVF]) could be useful in circumventing these problems and for delivering molecularly cloned genes into felid offspring. As an example, we already have proven the utility of AI for propagating mucopolysaccharidotic cats and for producing domestic cat x leopard cat hybrids useful for developing a high resolution genetic linkage map of the domestic cat. The latter will be useful for further understanding the genetic loci involved in neoplastic transformation and other disease states. Certain domestic cats also produce high numbers of structurally abnormal spermatozoa. Because men routinely produce many sperm pleiomor- phisms, the cat and its wild relatives are serving as ethically-attractive models for studying the impact of teratospermia. The ability to generate embryos "easily" by IVF, the question of the impact of poor quality ejaculates on fertilization, and a large loss of embryos after transfer are common problems to both the cat and human. Therefore, the felid taxon serves as one of the most important nonprimate models available for addressing these issues.